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Multilevel Amplitude and Phase Shift Keying Optical Transmission
Published in Le Nguyen Binh, Advanced Digital, 2017
The symbol duration is Ts = mTB with TB as the bit duration, and the symbol rate is fs = fB/m with fB = 1/TB as the bit rate. This shows that for a given bit rate, the symbol rate decreases if the modulation level increases. That means a higher bandwidth efficiency can be achieved by a higher-order modulation format. For the 16-QAM format, m = 4 bits are collected and mapped to one symbol from an alphabet with M = 16 possibilities. In comparison to the case of the binary modulation format, only m = 1 bit is mapped to one symbol from an alphabet with M = 2 possibilities. With 16-QAM format and a data source with a bit rate of fB = 40 Gbps, only a symbol rate of fs = 10 GBaud/s is necessary. From the commercial point of view, this means a 40 Gbps data rate can be transmitted with 10 Gbps transmission devices. In the case of binary transmission, the transmitter needs a symbol rate of fs = 40 GBaud/s. This means 16-QAM transmission requires four times slower transmission devices than that for the binary transmission. It is noted here that 10.7 Gsymbol/s is used as the symbol rate so as to compare the simulation results with the well-known 10.7 Gbps modulation schemes such as DPSK, CSRZ-DPSK, and so on. For a 107 Gbps bit rate, the transmission performance, that is, the sensitivity and the OSNR, can be scaled accordingly without any difficulty.
Convergence Technologies
Published in K.R. Rao, Zoran S. Bojkovic, Dragorad A. Milovanovic, Wireless Multimedia Communications, 2018
K.R. Rao, Zoran S. Bojkovic, Dragorad A. Milovanovic
One of the most important features of HSDPA is packet scheduling. The main goal of packet scheduling is to maximize system throughput while satisfying the QoS requirements of users. The packet scheduler determines to which user the shared channel transmission should be assigned at a given time. In HSDPA the packet scheduler can exploit short-term variations in the radio conditions of different users by selecting those with favorable instantaneous channel conditions for transmission, which is illustrated in Figure 2.10. This idea is based on the fact that good channel conditions allow for higher data rates (R) by using a higher-order modulation and coding schemes, thus resulting in increased system throughput.23,24
Digital Techniques for Mobile Radio
Published in Michel Daoud Yacoub, Foundations of Mobile Radio Engineering, 2019
The use of controllable redundancy (error-correcting codes) improves the error rate performance of the system at the expense of extra bits included in the data stream. Accordingly, the modulator must operate at higher bit rate, requiring extra channel bandwidth. Higher-order modulation schemes can be used to save bandwidth, but larger signal power is required to maintain the same error probability. Some alternative solutions have recently been proposed and they are briefly described next.
Error Rate Analysis of Different Modulation Schemes Over Shadowed Beaulieu-Xie Fading Channels
Published in IETE Journal of Research, 2022
Sisira Hawaibam, Aheibam Dinamani Singh
Figure 3 compares ABER performance versus the average SNR for Gray-coded RQAM. Gray-coded RQAM can accommodate M-ary PAM and M-ary SQAM. It is observed that ABER of higher modulation techniques, e 8-ary PAM and SQAM, is more than RQAM. In higher-order modulation, the data transmission rate is high. Hence, in the occurrence of channel fading, during a fade duration, several bits will be affected compared to that of lower order modulation. Therefore, the performance of 8-ary PAM is most affected due to fading. At ABER of , there is a difference of approximately 11 dB between RQAM and 8-ary PAM.
Multiple-period planning of Internet Protocol-over-Elastic Optical Networks
Published in Journal of Information and Telecommunication, 2019
Sridhar Iyer, Shree Prakash Singh
The working of the proposed multi-period planning technique is shown in Figure 1. As shown in Figure 1(a), the proposed model is able to exploit the BVT’s flexible nature which is useful in multiple varied configurations for carrying the client traffic and further, also allows for a scalable design due to the fact that the increase in port rate of the client can be ensured by (i) increasing (if and when available) the optical carriers amount(s) or (ii) utilizing advanced (higher order) modulation formats. The aforementioned is then applicable in the following (subsequent) periods, and can then be combined with the possibility of the (i) regenerator(s) addition (with the use of advanced (higher order) modulation formats, there occurs a decrease in TR) and (ii) already installed regenerator(s)’s displacement. Furthermore, as shown in Figure 1(b), by resorting to the previous network state’s re-optimization which, in turn, leads to the exploitation of the IP grooming capability, spare capacity utilization can be enabled, in turn, ensuring the availability of the network resources.
Overview of the challenges and solutions for 5G channel coding schemes
Published in Journal of Information and Telecommunication, 2021
Madhavsingh Indoonundon, Tulsi Pawan Fowdur
When higher-order modulation is used, more bits are transmitted per symbol which allows higher throughputs to be achieved. However, the constellation points get closer to each other when the order of modulation is increased, which in turn increases the probability of erroneous demodulation of the QAM symbols.